src/data/merge_sources.py

# Generated by Claude Code -- 2026-02-08
"""Merge CDM data from multiple sources into unified training format.

Combines:
  1. ESA Kelvins dataset (103 features, labeled)
  2. Space-Track cdm_public (16 features, unlabeled — derive risk from PC)

Strategy:
  - Space-Track CDMs are grouped into "conjunction events" by (SAT_1_ID, SAT_2_ID, TCA_date)
  - Each event gets a time series of CDMs ordered by CREATED date
  - Risk label derived from final PC: high risk if PC > 1e-5 (same threshold as Kelvins)
  - Features that exist in both sources get unified column names
  - Missing features (e.g., covariance in Space-Track) are filled with 0

This gives us far more positive examples for training the risk classifier,
even though the Space-Track data has fewer features per CDM.
"""

import numpy as np
import pandas as pd
from pathlib import Path
from datetime import timedelta


# Mapping from Space-Track CDM_PUBLIC fields → unified column names
SPACETRACK_COLUMN_MAP = {
    "CDM_ID": "cdm_id",
    "CREATED": "created",
    "TCA": "tca",
    "MIN_RNG": "miss_distance",      # km in Space-Track
    "PC": "collision_probability",
    "SAT_1_ID": "sat_1_id",
    "SAT_1_NAME": "sat_1_name",
    "SAT1_OBJECT_TYPE": "t_object_type",
    "SAT1_RCS": "t_rcs",
    "SAT_1_EXCL_VOL": "t_excl_vol",
    "SAT_2_ID": "sat_2_id",
    "SAT_2_NAME": "sat_2_name",
    "SAT2_OBJECT_TYPE": "c_object_type",
    "SAT2_RCS": "c_rcs",
    "SAT_2_EXCL_VOL": "c_excl_vol",
    "EMERGENCY_REPORTABLE": "emergency_reportable",
}

# Risk threshold: PC > 1e-5 = high risk (matches ESA Kelvins: risk > -5)
RISK_THRESHOLD = 1e-5


def load_spacetrack_cdms(csv_path: Path) -> pd.DataFrame:
    """Load Space-Track CDM CSV and do initial cleaning."""
    df = pd.read_csv(csv_path)

    # Rename columns to unified format
    df = df.rename(columns=SPACETRACK_COLUMN_MAP)

    # Parse dates
    for col in ["created", "tca"]:
        if col in df.columns:
            df[col] = pd.to_datetime(df[col], errors="coerce")

    # Convert miss_distance to float
    if "miss_distance" in df.columns:
        df["miss_distance"] = pd.to_numeric(df["miss_distance"], errors="coerce")
        # Space-Track MIN_RNG is in km; ESA Kelvins miss_distance is in meters
        # Convert to meters for consistency
        df["miss_distance"] = df["miss_distance"] * 1000.0

    # Convert collision_probability to float
    if "collision_probability" in df.columns:
        df["collision_probability"] = pd.to_numeric(df["collision_probability"], errors="coerce")

    # Derive risk column (log10 of PC, matching ESA format)
    if "collision_probability" in df.columns:
        df["risk"] = np.where(
            df["collision_probability"] > 0,
            np.log10(df["collision_probability"].clip(lower=1e-30)),
            -30.0,
        )

    print(f"Loaded {len(df)} Space-Track CDMs from {csv_path.name}")
    return df


def group_into_events(df: pd.DataFrame) -> pd.DataFrame:
    """
    Group Space-Track CDMs into conjunction events.

    An 'event' is a sequence of CDMs for the same object pair with TCA
    values within 1 day of each other. Each event gets a unique event_id.
    """
    if df.empty:
        return df

    # Sort by object pair and TCA
    df = df.sort_values(["sat_1_id", "sat_2_id", "tca", "created"]).reset_index(drop=True)

    # Assign event IDs: same pair + TCA within 1 day = same event
    event_ids = []
    current_event = 0
    prev_sat1 = None
    prev_sat2 = None
    prev_tca = None

    for _, row in df.iterrows():
        sat1 = row.get("sat_1_id")
        sat2 = row.get("sat_2_id")
        tca = row.get("tca")

        same_pair = (sat1 == prev_sat1 and sat2 == prev_sat2)
        close_tca = False
        if same_pair and prev_tca is not None and pd.notna(tca) and pd.notna(prev_tca):
            close_tca = abs((tca - prev_tca).total_seconds()) < 86400  # 1 day

        if not (same_pair and close_tca):
            current_event += 1

        event_ids.append(current_event)
        prev_sat1 = sat1
        prev_sat2 = sat2
        prev_tca = tca

    df["event_id"] = event_ids

    # Compute time_to_tca: days from CDM creation to TCA (for each CDM in event)
    if "created" in df.columns and "tca" in df.columns:
        df["time_to_tca"] = (df["tca"] - df["created"]).dt.total_seconds() / 86400.0
        df["time_to_tca"] = df["time_to_tca"].clip(lower=0.0)

    n_events = df["event_id"].nunique()
    n_high_risk = 0
    if "risk" in df.columns:
        event_risks = df.groupby("event_id")["risk"].last()
        n_high_risk = (event_risks > -5).sum()

    print(f"Grouped into {n_events} events ({n_high_risk} high-risk)")
    return df


def compute_relative_speed_from_excl_vol(df: pd.DataFrame) -> pd.DataFrame:
    """Estimate relative speed from exclusion volumes if available."""
    # excl_vol is in km, but we can't derive speed from it alone
    # Just ensure the column exists for compatibility
    if "relative_speed" not in df.columns:
        df["relative_speed"] = 0.0
    return df


def align_with_kelvins_schema(
    spacetrack_df: pd.DataFrame,
    kelvins_df: pd.DataFrame,
) -> pd.DataFrame:
    """
    Align Space-Track data columns with Kelvins schema.
    Missing columns get filled with 0.
    """
    # Get all columns from Kelvins
    kelvins_cols = set(kelvins_df.columns)
    st_cols = set(spacetrack_df.columns)

    # Add missing numeric columns as 0
    for col in kelvins_cols:
        if col not in st_cols:
            spacetrack_df[col] = 0.0

    # Keep only columns that exist in Kelvins + our extra metadata
    extra_cols = {"sat_1_id", "sat_2_id", "sat_1_name", "sat_2_name",
                  "t_object_type", "collision_probability", "created", "tca",
                  "cdm_id", "emergency_reportable", "t_rcs", "c_rcs",
                  "t_excl_vol", "c_excl_vol", "source"}
    keep_cols = list(kelvins_cols | extra_cols)
    available = [c for c in keep_cols if c in spacetrack_df.columns]
    return spacetrack_df[available]


def merge_datasets(
    kelvins_train_df: pd.DataFrame,
    spacetrack_df: pd.DataFrame,
    offset_event_ids: bool = True,
) -> pd.DataFrame:
    """
    Merge Kelvins training data with Space-Track CDMs.

    Args:
        kelvins_train_df: ESA Kelvins training DataFrame
        spacetrack_df: Space-Track CDMs (already grouped into events)
        offset_event_ids: shift Space-Track event_ids to avoid collisions

    Returns:
        Combined DataFrame ready for model training
    """
    # Tag sources
    kelvins_train_df = kelvins_train_df.copy()
    kelvins_train_df["source"] = "kelvins"

    spacetrack_df = spacetrack_df.copy()
    spacetrack_df["source"] = "spacetrack"

    # Offset Space-Track event IDs to avoid collision with Kelvins IDs
    if offset_event_ids and "event_id" in kelvins_train_df.columns:
        max_kelvins_id = kelvins_train_df["event_id"].max()
        spacetrack_df["event_id"] = spacetrack_df["event_id"] + max_kelvins_id + 1

    # Align columns
    spacetrack_df = align_with_kelvins_schema(spacetrack_df, kelvins_train_df)

    # Concatenate
    combined = pd.concat([kelvins_train_df, spacetrack_df], ignore_index=True)

    # Fill any remaining NaN
    numeric_cols = combined.select_dtypes(include=[np.number]).columns
    combined[numeric_cols] = combined[numeric_cols].fillna(0)

    n_kelvins = kelvins_train_df["event_id"].nunique()
    n_st = spacetrack_df["event_id"].nunique()
    n_total = combined["event_id"].nunique()

    # Count high-risk events per source
    event_risk = combined.groupby(["event_id", "source"])["risk"].last().reset_index()
    n_hr_kelvins = ((event_risk["source"] == "kelvins") & (event_risk["risk"] > -5)).sum()
    n_hr_st = ((event_risk["source"] == "spacetrack") & (event_risk["risk"] > -5)).sum()

    print(f"\nMerged dataset:")
    print(f"  Kelvins:     {n_kelvins} events ({n_hr_kelvins} high-risk)")
    print(f"  Space-Track: {n_st} events ({n_hr_st} high-risk)")
    print(f"  Total:       {n_total} events ({n_hr_kelvins + n_hr_st} high-risk)")
    print(f"  Columns:     {len(combined.columns)}")

    return combined


def load_and_merge_all(data_dir: Path) -> tuple[pd.DataFrame, pd.DataFrame]:
    """
    Load all available data sources and merge into train/test DataFrames.

    Returns (train_df, test_df) — test is Kelvins-only (for fair comparison).
    """
    from src.data.cdm_loader import load_dataset

    # Load ESA Kelvins
    kelvins_dir = data_dir / "cdm"
    kelvins_train, kelvins_test = load_dataset(kelvins_dir)

    # Load Space-Track data if available
    spacetrack_dir = data_dir / "cdm_spacetrack"
    spacetrack_files = list(spacetrack_dir.glob("cdm_*.csv")) if spacetrack_dir.exists() else []

    if not spacetrack_files:
        print("\nNo Space-Track data found. Using Kelvins only.")
        return kelvins_train, kelvins_test

    # Load and merge all Space-Track CSVs
    st_dfs = []
    for f in spacetrack_files:
        if f.name.startswith("checkpoint"):
            continue
        df = load_spacetrack_cdms(f)
        df = group_into_events(df)
        df = compute_relative_speed_from_excl_vol(df)
        st_dfs.append(df)

    if st_dfs:
        all_st = pd.concat(st_dfs, ignore_index=True)
        # Re-assign event IDs after concatenation
        all_st = group_into_events(all_st)
        merged_train = merge_datasets(kelvins_train, all_st)
    else:
        merged_train = kelvins_train

    # Test set stays Kelvins-only for fair benchmarking
    return merged_train, kelvins_test